1889.] Geology and Pahcontology. 623 
the cell attains the greatest height, they are often anmilated at the 
base and centre by epithecal rings ; and l)udding often takes place 
slightly below the margin of the cell. 
The usual method of growth o{ this species is by lateral budding 
almost from the beginning, but sometimes a single cell attains a height 
of from seven to twelve mm. before new cells are formed. This spe- 
cies, as well as all other species of this genus known to me, are, or 
were originally (with one known exception) attached to the surface of 
some shell or other species of corals. The delineation of this species 
is here based upon over two hundred finely preserved specimens. 
Its range is, so far as known to me, confined exclusively to the 
Rockford shales, except in some cases where it occurs in the lime- 
stone which immediately underlies them. 
Pachyphyllum crassicostatum n. sp. — Coral, very coarse, growing in 
irregular, convex or slightly branching masses, from one and one-half 
to eleven centimetres in diameter ; central depre.ssions circular, from 
two to seven mm. in depth ; wall very thick and strong. Entire cell 
from one and one-fifth to about two and one-fifth centimetres in diam- 
eter, usually limited by a wall formed by the uniting of the costae 
of the adjoining cells ; and again, this feature is not always well 
shown, owing to the great irregularity in growth of some specimens. 
Rays numbering from thirty-one to sixty, often only half of which 
extend to the elevated perpendicularly perforate columella in the 
specimens the bottom of the cell is sometimes occupied by a well- 
defined, circular depression, instead of a columella. Rays and 
costse continuous, passing down the outside of the cell wall and over 
the intercellular spaces. Intercostal and interseptal spaces divided by 
numerous thin, straight or convex transverse partitions. 
The usual method of growth of this species is peculiar. Generally 
a large and very coarse curved cell will attain to the height (following 
the curvature of the specimen) of five and one-half centimetres 
or more before budding begins, which then takes place slightly 
below the margin of the cell, or some distance below. This descrip- 
tion is from specimens from Owens' Grove, Cerro Gordo county, and 
Floyd, Floyd county, Iowa. Specimens of a variety of this species 
occur at Rockford and Hackberry; and differing from those from 
Owens' Grove and Floyd in the method of growth (which is generally 
by budding from the first) in that the coralla do not attain to so great 
a size, and the bottom of the cells never being occupied by a depres- 
sion, as well as the (sometimes) slightly less coarse character of the 
